GA3218

GA3219 / GA3218 / GA3217 Venture™ Digital DSP System GA3219 / GA3218 / GA3217 Preliminary Data Sheet Features • SoundDesign™ Advanced Research • • • 128-band adaptive noise reduction adaptive feedback cancellation Description Venture is Gennum's premiere DSP product designed on the Voyageur™ platform. Combining the power and capabilities of Voyageur together with SoundDesign Advanced Research, Venture delivers cutting-edge features and high performance. Voyageur is Gennum's industry-leading programmable digital signal processing platform. SoundDesign Advanced Research is a Gennum developed methodology that couples state-of-the-art acoustic algorithms to ensure high-fidelity digital sound quality. Venture's adaptive noise reduction preserves perceived speech levels without causing distortion. It monitors noise levels independently in 128 individual bands. This strategy also employs advanced psychoacoustic models to eliminate audible noise and reduce the amount of perceptible artifacts introduced by the noise reduction process. Based on a phase cancellation method, Venture's adaptive feedback reduction algorithm provides increased maximum stable gain unlike other feedback strategies. Additionally, it features rapid adjustment for dynamic feedback situations and resistance to tonal inputs. In addition to these adaptive algorithms, Venture also supports the following features: FRONTWAVE directional processing, cross fading between audio paths for click-free memory changes, 8-band graphic equalizer, 8 generic biquad filters (configurable as parametric or other filter types), programming speed enhancements, optional peak clipping, flexible compression adjustments, programmable tones for memory change and low battery indicators, wideband gain, volume control and industry-leading security features to avoid cloning and software piracy. Available Venture configurations: • • • GA3219: Adaptive noise reduction and adaptive feedback canceller GA3218: Adaptive noise reduction GA3217: Adaptive feedback canceller 128-bit fingerprint security system and other security features to protect against device cloning and software piracy soft acoustic fade between memory changes FRONTWAVE® directional processing high fidelity audio CODEC 20-bit audio precision 95dB input dynamic range with HRX™ Headroom Extension 1, 2 or 4 channel WDRC compression 8-band graphic EQ 8 biquadratic filters drives zero-bias 2-terminal receivers 4 analog inputs 4 fully configurable memories with audible memory change indicator 2 memory select pads internal or external volume control AGCo with variable threshold, time constants, and optional adaptive release 16kHz or 8kHz bandwidth optimized programming speed thinSTAX™ packaging • • • • • • • • • • • • • • • • • thinSTAX PACKAGING • Hybrid typical dimensions: 0.215 x 0.124 x 0.065in. 5.46 x 3.15 x 1.65mm Proprietary and Confidential 32718 - 2 February 2005 1 of 24 www.gennum.com GA3219 / GA3218 / GA3217 Preliminary Data Sheet Block Diagram MS2 5 MS 4 TONE GENERATOR VB 6 POR CIRCUITRY 7 VBP VREG 1 VOLTAGE REGULATOR MEMORY SELECT POST BIQUAD FILTERS CROSS FADER PEAK CLIPPER D/A HBRIDGE 8 9 OUTOUT+ FMIC 15 RMIC 14 TIN DAI 2 3 M U X A/D A/D MIC/TELECOIL COMPENSATION F R O N T W A V E PRE BIQUAD FILTERS AGCO VOLUME CONTROL POST BIQUAD FILTERS CONTROL A/D 10 PGND 13 VC FEEDBACK CANCELLER WIDEBAND GAIN MGND 16 FREQUENCY BAND ANALYSIS SDA 12 PROGRAMMING INTERFACE 128 bands FREQUENCY BAND SYNTHESIS WDRC (1,2,4 channels) Noise Reduction (128 bands) CLOCK GENERATOR Graphic EQ (8 bands) EEPROM 11 GND Hybrid block diagram Proprietary and Confidential 32718 - 2 February 2005 2 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet Contents Features ........................................................................................................................1 thinSTAX PACKAGING.................................................................................................1 Description ....................................................................................................................1 1. Pad Connection.........................................................................................................4 2. Absolute Maximum Rating ........................................................................................4 3. Electrical Characteristics ...........................................................................................5 4. Typical Applications ..................................................................................................7 5. Venture Overview......................................................................................................9 6. Signal Path..............................................................................................................10 7. Functional Block Description ...................................................................................11 7.1 Adaptive Feeback Canceller .........................................................................11 7.2 Adaptive Noise Reduction .............................................................................11 7.3 A/D and D/A Converters ...............................................................................12 7.4 HRX Head Room Expander ..........................................................................12 7.5 FRONTWAVE Directionality .........................................................................12 7.6 Channel Processing ......................................................................................13 7.7 Telecoil Path .................................................................................................14 7.8 Graphic Equalizer .........................................................................................14 7.9 Biquad Filters ................................................................................................14 7.10 Volume Control ...........................................................................................15 7.11 AGCo and Peak Clipper ..............................................................................15 7.12 Memory Select Switches .............................................................................16 7.12.1 Momentary Switch on MS..................................................................16 7.12.2 Momentary Switch on MS, Static Switch on MS2 (jump to last memory) ...................................................................................16 7.12.3 Static Switch on MS and MS2 ...........................................................17 7.12.4 Static Switch on MS, Static Switch on MS2 (jump to last memory) ...................................................................................17 7.13 Audible Memory Change Indicator ..............................................................18 7.14 Tone Generator ...........................................................................................19 7.15 Cross Fader ................................................................................................19 7.16 Power-On/Power-Off Behavior and Low Battery Indicator ..........................19 7.17 Software And Security ................................................................................21 7.18 SDA Communication ...................................................................................21 7.19 Power Management ....................................................................................21 8. Package Dimensions ..............................................................................................22 8.1 Pad Location .................................................................................................23 9. Revision History ......................................................................................................24 Proprietary and Confidential 32718 - 2 February 2005 3 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 1. Pad Connection PGND 10 OUT+ 9 16 GND 11 SDA 12 VC 13 RMIC 14 FMIC 15 OUT- 8 MGND 7 VBP 6 VB 5 MS2 4 MS 3 DAI 2 TIN 1 VREG Figure 1-1: Pad Connection 2. Absolute Maximum Rating Parameter Operating Temperature Range Storage Temperature Range Absolute Maximum Power Dissipation Maximum Operating Supply Voltage Absolute Maximum Supply Voltage Value 0°C to 40°C -20°C to 70°C 25mW 1.5VDC 2VDC Proprietary and Confidential 32718 - 2 February 2005 4 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 3. Electrical Characteristics Table 3-1: Electrical Characteristics Conditions: VBAT = 1.25V Temperature = 25°C Parameter Hybrid Current Symbol IAMP IAMP Conditions With adaptive features 8kHz bandwidth With adaptive features 16kHz bandwidth Ramp down Ramp up – – 32kHz sampling rate VIN = -40dBV VIN = -15dBV, HRX - ON – Min – – 0.93 1.06 100k – – – – 1.945 Typ 925 1150 0.95 1.1 – 125 16 – – 2.048 Max – – 0.97 1.16 – – – 1 3 2.151 Units µA µA V V cycles Hz kHz % % MHz Minimum Operating Supply Voltage Supply Voltage Turn On Threshold EEPROM Burn Cycles Low Frequency System Bandwidth High Frequency System Bandwidth Total Harmonic Distortion THD at Maximum Input Clock Frequency VBOFF VBON – – – THD THDM fclk Regulator Regulator Voltage VREG – 0.87 0.90 0.93 V Input Input Referred Noise Input Impedance Anti-aliasing Filter Rejection Maximum Input Level Input Dynamic Range A/D Dynamic Range IRN ZIN – – – – Bandwidth 100Hz - 8KHz – ƒ = ƒCLK - 8kHz, VIN = -40dBV – HRX - ON Bandwidth 100Hz - 8KHz Bandwidth 100Hz - 8KHz – – – – – – – 16 80 -15 95 86 -106 – – – – – dBV kΩ dB dBV dB dB Output D/A Dynamic Range Output Impedance – ZOUT – – – – 83 – – 15 dBV Ω Proprietary and Confidential 32718 - 2 February 2005 5 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet Table 3-1: Electrical Characteristics (Continued) Conditions: VBAT = 1.25V Temperature = 25°C Parameter Volume Control Volume Control Resistance Symbol Conditions Min Typ Max Units RVC RVC Two-terminal connection Three-terminal connection – 160 100 – 200 – 42 240 1000 – kΩ kΩ dB Volume Control Range ∆A SDA Input Logic 0 Voltage Logic 1 Voltage – – – – 0 1 – – 0.3 1.3 V V SDA Output Standby Pull Up Current Sync Pull Up Current Logic 0 Current (Pull Down) Logic 1 Current (Pull Up) Synchronization Time (Synchronization Pulse Width) – – – – TSYNC TSYNC TSYNC TSYNC TSYNC TSYNC TSYNC TSYNC – – – – Baud = 0 Baud = 1 Baud = 2 Baud = 3 Baud = 4 Baud = 5 Baud = 6 Baud = 7 1.4 450 225 225 237 118 59 29.76 14.88 7.44 3.72 1.86 2 500 250 250 250 125 62.5 31.25 15.63 7.81 3.91 1.95 2.6 550 275 275 263 132 66 32.81 16.41 8.20 4.10 2.05 µA µA µA µA µs µs µs µs µs µs µs µs MS Input Pull Down Resistance Logic 1 Voltage Rising Edge Threshold Falling Edge Threshold Hysteresis – – – – – – – – – – – VREG 0.5 0.25 0.1 1 – 0.69 0.45 0.24 – VB 0.9 0.5 0.4 MΩ V V V V Proprietary and Confidential 32718 - 2 February 2005 6 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet Table 3-1: Electrical Characteristics (Continued) Conditions: VBAT = 1.25V Temperature = 25°C Parameter MS2 Input Pull Down Resistance Logic 1 Voltage Rising Edge Threshold Falling Edge Threshold Hysteresis Symbol Conditions Min Typ Max Units – – – – – – – – – – – VREG 0.5 0.25 0.1 1 – 0.69 0.45 0.24 – VB 0.9 0.5 0.4 MΩ V V V V 4. Typical Applications All resistors in ohms, all capacitors in farads unless otherwise stated. VB 5 4 TONE GENERATOR 6 POR CIRCUITRY 7 OUT 1 VOLTAGE REGULATOR MEMORY SELECT POST BIQUAD FILTERS CROSS FADER PEAK CLIPPER D/A HBRIDGE 8 LP FILTER 15 3k9 A/D 14 3k9 2 1k M U X 3 1k A/D MIC/TELECOIL COMPENSATION F R O N T W A V E PRE BIQUAD FILTERS FEEDBACK CANCELLER 9 AGCO VOLUME CONTROL POST BIQUAD FILTERS CONTROL A/D WIDEBAND GAIN 10 13 200k 16 FREQUENCY BAND ANALYSIS 12 PROGRAMMING INTERFACE 128 bands FREQUENCY BAND SYNTHESIS WDRC (1,2,4 channels) Noise Reduction (128 bands) CLOCK GENERATOR Graphic EQ (8 bands) EEPROM 11 Figure 4-1: Test Circuit Proprietary and Confidential 32718 - 2 February 2005 7 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet VB 5 4 TONE GENERATOR 6 POR CIRCUITRY 7 1 VOLTAGE REGULATOR MEMORY SELECT POST BIQUAD FILTERS CROSS FADER PEAK CLIPPER D/A HBRIDGE 8 9 Knowles or Sonion zero-bias receiver 15 14 2 3 M U X A/D A/D MIC/TELECOIL COMPENSATION F R O N T W A V E PRE BIQUAD FILTERS FEEDBACK CANCELLER AGCO VOLUME CONTROL POST BIQUAD FILTERS CONTROL A/D WIDEBAND GAIN 10 13 16 FREQUENCY BAND ANALYSIS 12 PROGRAMMING INTERFACE 128 bands FREQUENCY BAND SYNTHESIS WDRC (1,2,4 channels) Noise Reduction (128 bands) CLOCK GENERATOR Graphic EQ (8 bands) EEPROM 11 Figure 4-2: Typical Application Circuit VC CS44 + Rear Mic Zero Biased Receiver + Front Mic MS switch (N.O.) T-coil Figure 4-3: Typical Hearing Instrument Assembly Diagram Proprietary and Confidential 32718 - 2 February 2005 8 of 24 + - GA3219 / GA3218 / GA3217 Preliminary Data Sheet 5. Venture Overview Venture Digital is a DSP system with adaptive algorithms that run on the Voyageur™ hardware platform. This hardware platform is a combination of a DSP core and a high fidelity audio CODEC. As well, thinSTAX packaging provides easy integration into a wide range of applications from CIC to BTE. The audio functions implemented on the CODEC include tone generation, peak clipping and cross fading between audio paths. The DSP core implements FRONTWAVE directional processing, programmable filters, adaptive algorithms, compression, wideband gain, and volume control. The adaptive algorithms include Adaptive Noise Reduction and Adaptive Feedback Cancellation. The Adaptive Noise Reduction reduces audible noise in a low distortion manner while preserving perceived speech levels. The Adaptive Feedback Canceller reduces acoustic feedback while offering robust performance against pure tones. As well, Venture contains security features to protect clients' Intellectual Property against device cloning and software piracy. Venture utilizes the power and capabilities of Voyageur to deliver advanced features and enhanced performance previously unavailable to a product in its class. This data sheet is part of a set of documents available for this product. Please refer to “Getting Started with Venture Digital”, document #33350, for a list of other documents. Proprietary and Confidential 32718 - 2 February 2005 9 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 6. Signal Path There are two main audio input signal paths. The first path contains the Front Microphone and second path contains the Rear Microphone, Telecoil or Direct Audio input as selected by a programmable MUX. The front microphone input is intended as the main Microphone audio input for single microphone applications. In FRONTWAVE operation, a multimicrophone signal is used to produce a directional hearing instrument response. The two audio inputs are buffered, sampled and converted into digital form using dual A/D converters. The digital outputs are converted into a 32kHz or 16kHz, 20-bit digital audio signal. Further IIR filter blocks process the front microphone and rear microphone signals. One biquad filter is used to match the rear microphone's gain to that of the front microphone. After that, another filter is used to provide an adjustable group delay to create the desired polar response pattern during the calibration process. In the Telecoil mode gains are trimmed during Cal/Config process to compensate for microphone/telecoil mismatches. The FRONTWAVE block is followed by four cascaded biquad filters: "pre1", "pre2", "pre3" and “pre4". These filters can be used for frequency response shaping before the signal goes through channel and adaptive processing. The channel and adaptive processing consists of • • • • • • frequency band analysis 1, 2 or 4 channel WDRC 8 logarithmically spaced band frequency shaping (graphic EQ) 128 frequency band adaptive noise reduction frequency band synthesis phase cancellation adaptive feedback reduction After the processing the signal goes through two more biquad filters, "post1" and "post2", the Wideband Gain and Volume Control. These biquad filters are followed by the AGCo block, two more biquad filters, post3" and "post4", and the Peak Clipper. The last stage in the signal path is the D/A H-bridge. Proprietary and Confidential 32718 - 2 February 2005 10 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 7. Functional Block Description 7.1 Adaptive Feeback Canceller The Adaptive Feedback canceller (AFC) reduces acoustic feedback by forming an estimate of the hearing aid feedback signal and then subtracting this estimate from the hearing aid input. Therefore the forward path of the hearing is not affected. Unlike adaptive notch filter approaches, Venture's AFC does not reduce the hearing aid's gain. The AFC is based on a time-domain model of the feedback path. Venture’s second generation AFC exhibits greatly improved resistance to tonal inputs. Feedback path H + - Σ G H' Estimated feedback Figure 7-1: Adaptive Feedback Canceller (AFC) block diagram 7.2 Adaptive Noise Reduction The noise reduction algorithm is built upon a high resolution 128-band filterbank enabling precise removal of noise. The algorithm monitors the signal and noise activities in these bands, and imposes a carefully calculated attenuation gain independently in each of the 128 bands. The noise reduction gain applied to a given band is determined by a combination of three factors: • • • Signal-to-Noise Ratio (SNR) Masking threshold Dynamics of the SNR per band. The SNR in each band determines the maximum amount of attenuation that will be applied to the band; the poorer the SNR, the greater the amount of attenuation. Simultaneously, in each band, the masking threshold variations resulting from the energy in other adjacent bands is taken into account. Finally, the noise reduction gain is also adjusted to take advantage of the natural masking of 'noisy' bands by speech bands over time. Based on this approach, only enough attenuation is applied to bring the energy in each 'noisy' band to just below the masking threshold. This prevents excessive amounts of attenuation from being applied and thereby reduces unwanted artifacts 32718 - 2 February 2005 Proprietary and Confidential 11 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet and audio distortion. The Noise Reduction algorithm efficiently removes a wide variety of types of noise, while retaining natural speech quality and level. 7.3 A/D and D/A Converters The system's two A/D converters are 2nd-order sigma-delta modulators, which operate at a 2.048MHz sample rate. The system's two audio inputs are pre-conditioned with antialias filtering and programmable gain pre-amplifiers. These analog outputs are over sampled and modulated to produce two, 1-bit pulse density modulated (PDM) data streams. The digital PDM data is then decimated down to pulse-code modulated (PCM) digital words at the system sampling rate of 32kHz. The D/A is comprised of a digital, 3rd-order sigma-delta modulator and an H-bridge. The modulator accepts PCM audio data from the DSP path and converts it into a 32-times over-sampled, 1-bit PDM data stream, which is then supplied to the H-bridge. The H-bridge is a specialized CMOS output driver used to convert the 1-bit data stream into a low-impedance, differential output voltage waveform suitable for driving zero-biased hearing aid receivers. 7.4 HRX Head Room Expander Venture has an enhanced Head Room Expander (HRX) circuit, which increases the input dynamic range of Venture without any audible artifacts. This is accomplished by dynamically adjusting the preamplifier's gain and the post-A/D attenuation depending on the input level. 7.5 FRONTWAVE Directionality The FRONTWAVE block provides the resources necessary to implement directional microphone processing. The block accepts inputs from both a front and rear microphone and provides a synthesized directional microphone signal as its output. The directional microphone output is obtained by delaying the rear microphone signal and subtracting it from the front microphone signal. Various microphone response patterns can be obtained by adjusting the time delay. The FRONTWAVE circuit also provides a fixed filter for compensating the sensitivity and frequency response differences between microphones. The filter parameters are adjusted during product calibration. A dedicated biquad filter following the FRONTWAVE block has been allocated for low frequency equalization to compensate for the 6dB/octave roll off in frequency response that occurs in directional mode. The amount of low frequency equalization that is applied can be determined during product calibration. Gennum recommends using matched microphones with FRONTWAVE, although calibration is fully possible using unmatched microphones. Proprietary and Confidential 32718 - 2 February 2005 12 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 7.6 Channel Processing Figure 7-2 represents the I/O characteristic of independent AGC channel processing. The I/O curve can be divided into four main regions: • • • • low input level expansion (squelch) region low input level linear region compression region high input level linear region (return to linear) 0 -10 -20 High Level Gain OUTPUT LEVEL (dBV) -30 -40 -50 -60 -70 -80 -90 -100 -120 -110 -100 -90 Low Level Gain Compression Ratio Upper Threshold Lower Threshold Squelch Threshold -80 -70 -60 -50 -40 -30 -20 INPUT LEVEL (dBV) Figure 7-2: Independent Channel I/O Curve Flexibility The I/O characteristic of the channel processing can be adjusted in six ways: • • • • • • squelch threshold (SQUELCHTH) low level gain (LLGAIN) lower threshold (LTH) high level gain (HLGAIN) upper threshold (UTH) compression ratio (CR) To ensure that the I/O characteristics are continuous it is necessary to limit adjustment to a maximum of four of the available five parameters. During Parameter Map creation it is necessary to select four parameters as user adjustable (or fixed) and allow one parameter to be calculated. The squelch region within each channel implements a low level noise reduction scheme (1:2 or 1:3 expansion ratio) for listener comfort. This scheme operates in quiet listening environments (programmable threshold) to reduce the gain at very low levels. The number of compression channels is programmable in ARKonline and can be 1, 2 or 4. Proprietary and Confidential 32718 - 2 February 2005 13 of 24 GA3219 / GA3218 / GA3217 Preliminary Data Sheet 7.7 Telecoil Path The telecoil input is calibrated during the Cal/Config process. To compensate for the telecoil/microphone frequency response mismatch, a first order filter with 500Hz corner frequency is implemented. Through ARKonline it is possible to implement a telecoil compensation filter with an adjustable corner frequency. To accommodate for the gain mismatch, the telecoil gain is adjusted to match the microphone gain at 500Hz or 1kHz (default) and is selectable in ARKonline. There is also a telecoil gain adjustment parameter, which can be enabled in ARKonline and set in IDS that will allow for manual adjustment of the telecoil gain compensation. 7.8 Graphic Equalizer Venture has an 8 band graphic equalizer. The bands are spaced logarithmically, and each one provides up to 24dB of gain adjustment in 1dB increments. 7.9 Biquad Filters Additional frequency shaping can be achieved by configuring generic biquad filters. The transfer function for each of the biquad filters is as follows: b0 + b1 * z-1 + b2 * z-2 H(z) = ______________________ 1 + a1 * z-1 + a2 * z-2 Note that the a0 coefficient is hard-wired to always be a 1. The coefficients are each 16 bits in length and include one sign bit, one bit to the left of the decimal point, and 14 bits to the right of the decimal point. Thus, before quantization, the floating-point coefficients must be in the range -2.0