MX118

MX118 FULL-DUPLEX SCRAMBLER FOR CORDLESS TELEPHONES Features Full-Duplex Audio Processing On-Chip “Brick-wall” Filters (300-3000 Hz) Low Voltage CMOS High Baseband and Carrier Rejection Excellent Audio Quality ECPA* Qualified Voice Protection Applications Cordless Telephones & Wireless PBXs Battery Powered Portability MX118P (16 pin PDIP) MX118DW (SOIC-16) Description The MX118 is a full-duplex frequency inversion scrambler that secures cordless telephone conversations. The two audio paths, C1 and C2, are identical and independent. Each consists of the following: 1) A 10th order lowpass filter cut off at 3.1 kHz. 2) A balanced modulator with high baseband and carrier rejection. 3) A 3.3 kHz inversion carrier (injection tone). 4) A 14th order bandpass filter (300-3000 Hz). 5) Input op-amps with externally adjustable gain. The MX118 uses CMOS switched-capacitor filter technology and operates from a single supply in the range of 3.0 V to 5.5 V. The inversion carrier's frequency and filter switching clock are generated on-chip using an external 4.433619 MHz crystal or clock input. Figure 1 - Simplified Signal Paths * Electronics Communications Privacy Act (Title 18 US Code 2510 et seq.). MX118 Figure 2 - Block Diagram ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ ➤ Component Value R1 1.0MΩ C1 1.0µF C2 33.0pF C3 47.0pF C4 0.47µF C5 1.0µF C6 1.0µF X1 4.433619 MHz Tolerances: R = ±10%, C = ±20% Notes: 1. Xtal circuitry shown is in accordance with MX-COM's Application Note on Crystal Oscillators (see Appendix). Figure 3 - Recommended External Components Page 2 MX-COM, INC. MX118 Pin Function Chart Pin 1 2 3 Function Xtal: This is the output of the clock oscillator inverter. No Connection. C1 Filter Output: This is the output of the channel 1 input filter. It should be coupled to pin 4 (C1 Balanced Modulator Input) by a 1.0 µF cap. See Figure 3. C1 Balanced Modulator Input: This is the input to the channel 1 balanced modulator. Internally biased at VDD/2, it should be coupled to pin 3 (C1 Filter Output) by capacitor C2. VSS: Negative supply (GND). C1 Output: This is the analog output of channel 1. It is internally biased at VDD/2. C1 Gain Amp Output: This is the output pin of the channel 1 gain adjusting op-amp. See Figure 4 for test gain setting components. C1 Input: This is the analog signal input to channel 1. This input is to a gain adjusting op-amp whose gain is set by internal components. See Figure 4. C2 Input: This is the analog signal input to channel 2. This input is to a gain adjusting op-amp whose gain is set by internal components. See Figure 4. C2 Gain Amp Output: This is the output pin of the channel 2 gain adjusting op-amp. See Figure 4 for test gain setting components. C2 Output: This is the analog output of channel 2. It is internally biased at VDD/2. VBIAS: This is the analog bias line at VDD/2. It should be coupled to VSS by a 1.0 µF or greater capacitor. See Figure 3. C2 Balanced Modulator Input: This is the input to the channel 2 balanced modulator. Internally biased at VDD/2, it should be coupled to pin 14 (C2 Filter Output) by capacitor C7. C2 Filter Output: This is the output of the channel 1 input filter. It should be coupled to pin 13 (C2 Balanced Modulator Input) by a 1.0 µF capacitor. See Figure 3. VDD: Positive supply of 3.0 V to 5.5 V. Xtal/Clock: 4.433619 MHz or an externally derived clock is injected at this pin. (See Figure 3.) 4 5 6 7 8 9 10 11 12 13 14 15 16 MX-COM, INC. Page 3 MX118 Page 4 MX-COM, INC. MX118 Application Information Figure 5 - Typical Audio Frequency Response of a Single Scrambled or De-scrambled Channel System Gains When calculating the external components for the operation of the MX118 the following should be considered: a) The input Lowpass Filter has a typical gain of 0.5 dB. b) The Balanced Modulator has a typical attenuation of 4.0 dB. c) The Output Bandpass Filter has a typical gain of 4.5 dB. How Inver verter How the Inverter Works Carrier Frequency minus Input Voice Frequency equals Scrambled Voice Frequency. Figure 6 - An Explanation of the MX118 Scramble Operation MX-COM, INC. Page 5 MX118 Specifications Absolute Maximum Ratings Exceeding the maximum rating can result in device damage. Operation of the device outside the operating limits is not suggested. Supply Voltage Input Voltage at any pin (Ref. VSS = 0V) Output sink/source current supply pins other pins Total Device Dissipation @ 25°C Derating Operating Temperature Storage Temperature -0.3 to 7.0 V -0.3V to (VDD + 0.3V) ±30mA ±20mA 800mW max. 10mW/°C -10°C to +70°C -40°C to +85°C Operating Limits All devices were measured under the following conditions unless otherwise noted. VDD = 3.75 V TAMB = 25°C Clock = 4.433619 MHz Audio Level 0dB Ref. = 387 mVrms @ 1 kHz Noise Bandwidth = 30kHz Characteristics Characteristics See Note Min. Typ. Max. Unit V mA MΩ Ω kΩ Static Values Supply Voltage 3.0 3.75 5.5 Supply Current 4.0 6.0 Input Impedance, Amplifiers 1.0 10.0 Output Impedance C1, C2 200 Amplifiers 10.0 Logic 1 Voltage 70% VDD Logic 0 Voltage 30% VDD On-Chip Xtal Oscillator RIN 10.0 ROUT 10.0 Inverter Gain 10.0 Gain/Bandwidth Product 10.0 Dynamic Values (Single Channel) Analog Signal Input Levels -16.0 +3 Carrier Breakthrough 1,2 -64.0 Baseband Breakthrough 1,2 -50.0 Carrier Frequency 5 3299 Analog Output Noise 3 -47.0 -42.0 Upper Cut-off Frequency (-3dB) 3100 Passband Ripple (300 to 2950 Hz) -1.5 +1.5 Attenuation at 3.3 kHz 30.0 34.0 Passband Gain -2 0.5 +3 Overall Modulated or De-Modulated Channel Response (Scrambler-Descrambler End-to-End) Passband Frequencies 300 2950 Passband Ripple -3 +2 Passband Gain @ 1 kHz 4 0 1.0 3.0 Distortion 1 3.0 Low Frequency Attenuation @ 150 Hz 26 34 NOTES 1. Measured with Input Level -3 dB. 2. Single Modulated Channel. 3. Short circuit input, any analog output, in 30 kHz bandwidth. 4. Op Amp gain 0 dB. 5. Accuracy dependent on Xtal/clock. MΩ kΩ V/V MHz dB dB dB Hz dB Hz dB dB dB Hz dB dB % dB Page 6 MX-COM, INC. CML Microcircuits COMMUNICATION SEMICONDUCTORS CML Product Data In the process of creating a more global image, the three standard product semiconductor companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc (USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA) Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML Microcircuits. These companies are all 100% owned operating companies of the CML Microsystems Plc Group and these changes are purely changes of name and do not change any underlying legal entities and hence will have no effect on any agreements or contacts currently in force. CML Microcircuits Product Prefix Codes Until the latter part of 1996, the differentiator between products manufactured and sold from MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX respectively. These products use the same silicon etc. and today still carry the same prefixes. In the latter part of 1996, both companies adopted the common prefix: CMX. This notification is relevant product information to which it is attached. CML Microcircuits (USA) [formerly MX-COM, Inc.] Product Textual Marking On CML Microcircuits (USA) products, the ‘MX-COM’ textual logo is being replaced by a ‘CML’ textual logo. Company contact information is as below: CML Microcircuits (UK)Ltd COMMUNICATION SEMICONDUCTORS CML Microcircuits (USA) Inc. COMMUNICATION SEMICONDUCTORS CML Microcircuits (Singapore)PteLtd COMMUNICATION SEMICONDUCTORS Oval Park, Langford, Maldon, Essex, CM9 6WG, England Tel: +44 (0)1621 875500 Fax: +44 (0)1621 875600 uk.sales@cmlmicro.com www.cmlmicro.com 4800 Bethania Station Road, Winston-Salem, NC 27105, USA Tel: +1 336 744 5050, 0800 638 5577 Fax: +1 336 744 5054 us.sales@cmlmicro.com www.cmlmicro.com No 2 Kallang Pudding Road, 09-05/ 06 Mactech Industrial Building, Singapore 349307 Tel: +65 7450426 Fax: +65 7452917 sg.sales@cmlmicro.com www.cmlmicro.com D/CML (D)/2 May 2002