BA6110FS

BA6110FS Standard ICs Voltage controlled operational amplifier BA6110FS The BA6110FS is a low-noise, low-offset programmable operational amplifier. Offering superb linearity over a broad range, this IC is designed so that the forward direction conductivity (gm) can be changed, making it ideal for applications such as voltage control amplifiers (VCA), voltage control filters (VCF) and voltage control oscillators (VCO). Distortion reduction circuitry improves the signal-to-noise ratio by a significant 10dB at a distortion rate of 0.5% in comparison with products not equipped with this feature. When used as a voltage control amplifier (VCA), a high S / N ratio of 86dB can be achieved at a distortion rate of 0.5%. The open loop gain is determined by the control current and an attached gain determining resistance RL, enabling a wide range of settings. In addition, a built-in low-impedance output buffer circuit reduces the number of attachments. !Applications Electronic volume controls Voltage-controlled impedances Voltage-controlled amplifiers (VCA) Voltage-controlled filters (VCF) Voltage-controlled oscillators (VCO) Multipliers Sample holds Schmitt triggers !Features 1) Low distortion rate. (built-in distortion reduction bias diode) 2) Low noise. 3) Low offset voltage. (VIO = 3m VMax). !Block diagram BUFFER INPUT VCA OUTPUT 4) Built-in output buffer. 5) Variable gm with superb linearity across three decade fields. BA6110FS BUFFER OUTPUT 16 15 14 13 12 11 10 1/2 – BUFFER + 1/2 VCC 1 2 3 4 5 6 7 N.C. N.C. INPUT BIAS N.C. POSITIVE INPUT NEGATIVE INPUT CONTROL INPUT N.C. – VEE 9 8 N.C. N.C. N.C. VCC BA6110FS Standard ICs !Internal circuit configuration 11 OUT 12 Buffer IN 15 VCC Current mirror (1) Current mirror (2) Current mirror (4) R4 R5 14 Buffer OUT Positive input 1 D1 D2 Negative input 3 Current mirror (3) Q13 Q14 Q17 Q18 R1 5 Input bias Q1 Q2 Q3 Q5 Q4 Q6 Q9 Q10 Q12 Q7 Q8 Q11 R2 R3 Current mirror (5) Q15 Q16 9 VEE Control pin 7 Fig.1 !Absolute maximum ratings (Ta = 25°C) Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Maximum control current Symbol VCC Pd Topr Tstg IC Max. Limits 34 300∗1 – 20 ~ + 70 – 55 ~ + 125 500 Unit V mW ˚C ˚C µA *1 Reduced by 3mW for each increase in Ta of 1˚C each 25˚C. !Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 15V, VEE = – 15V) Parameter Quiescent current Pin 7 bias current Distortion Forward transmission conductance Pin 6 maximum output voltage Pin 8 maximum output voltage Pin 6 maximum output current Residual noise 1 Residual noise 2 Discontinuous noise Leakage level Symbol IQ I7PIN THD gm | VOM6 | | VOM8 | | IOM6 | VN1 VN2 VNP2 L (Leak) Min. 0.9 — — Typ. 3.0 0.8 0.2 Max. 6.0 5 1 Unit µA % µs V V µA Conditions Measurement circuit mA ICONTROL = 0µA — ICONTROL = 200µA, VI = 5mVrms ICONTROL = 500µA ICONTROL = 500µA RL = 47kΩ ICONTROL = 500µA Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 Fig.2 4800 8000 12000 12 9 300 — — — — 14 11 500 – 94 – 74 10.5 – 94 — — 650 – 90 – 66 11.5 – 75 ICONTROL = 0µA, BPF dBm (30 ~ 320kHz, 3dB, 6dB / OCT) dBm dB dBm ICONTROL = 200µA, BPF (30 ~ 20kHz, 3dB, 6dB / OCT) ICONTROL = 200µA, BPF (30 ~ 20kHz, 3dB, 6dB / OCT) ICONTROL = 0µA, VIN = – 30dBm fIN = 20kHz BA6110FS Standard ICs !Measurement circuit S4 27kΩ 10µF 1kΩ 1 2 V 600Ω 3 1kΩ 9 2 1 S2 1V 3 S3 3 2 7 1 5 S7 S1 1 11 12 15 S5 D.V mA S0 VCC = + 10V + 1 BA6110FS 14 47kΩ 30 ~ 20kHz BPF 1 S6-2 2 2 S6-1 V.V THD DV 500µA→ 200µA→ 1 2 150kΩ 40dB AMP VEE = – 10V Vmp Fig.2 !Circuit discription The BA6110FS is configured of an operational amplifier which can control the forward propagation conductance (gm) using the control current, an input biascompensating diode used to eliminate distortion created by the amplifier’s differential input, a bias setter, and an output buffer. In the operational amplifier, Pin 1 is the positive input and Pin 3 is the negative input. Pin 7 is the control pin which determines the differential current. Pin 11 is the output pin which determines the open loop gain using the external resistor and the control current. This section describes the circuit operation of this operational amplifier. Transistors Q13 and Q14 form the differential input for the operational amplifier, while transistors Q7 to Q12 are composed of the current mirror circuits. The current mirror absorbs current from the differential input common emitter which is equal to the control current flowing into the Pin 7 control pin. If the differential input VIN = 0 at this point, then 1 / 2 Ic is supplied to the Q13 and Q14 collectors and the other half passes through the current mirrors (3) and (4). The output of current mirror (3) which is the differential active load is inverted by current mirror (5), and is balanced with the output of current mirror (4), also an active load. If the differential input changes, the current balance changes. The output current is on Pin 11. An output voltage can be generated using an external resistance. For the open loop gain of this operational amplifier, if the Pin 7 control current is ICONTROL and the Pin 11 external resistance is RO, then: Av = gm · RO = ICONTROL × RO KT 2q To eliminate the distortion created by the differential input, the input bias diode and its bias circuit consist of the following: bias diodes D1 and D2, current mirrors (1) and (2), and the Pin 5 bias pin current mirror that consists of the transistors Q1 to Q6 and the resistance R1. This circuit eliminates the distortion that occurs as a result of using the differential input open loop. In the buffer circuit, Pin 12 is the buffer input and Pin 14 is the buffer output. In the buffer circuit, the emitter follower consists of the active load of the NPN transistor, Q17, and its active load, Q16. The VF difference created by the emitter follower is eliminated by the emitter follower which consists of the PNP transistor Q18 and resistor R5. Also, the gain is determined by the ratio of the signal source resistance RIN and the diode impedance. BA6110FS Standard ICs !Attached components (1) Positive input (Pin 1) This is the differential positive input pin. To minimize the distortion due to the diode bias, an input resistor is connected in series with the signal source. By increasing the input resistance, distortion is minimized. However, the degree of improvement for resistances greater than 10kΩ is about the same. An input resistance of 1kΩ to 20kΩ is recommended. (2) Negative input (Pin 3) This is the differential negative input pin. It is grounded with roughly the same resistance value as that of the positive input pin. The offset adjustment is also connected to this pin. Make sure a sufficiently high resistance is used, so as not to disturb the balance of the input resistance (see Figure 3). (3) Input bias diode (Pin 5) The input bias diode current (ID) is determined by this pin. The IC input impedance when the diode is biased, if the diode bias current is ID, is expressed as follows: Rd = 26 ID (mA) (Ω) By changing the ICONTROL current on Pin 7, the differential gain can be changed. The gain (AV), if the resistance of Pin 11 is RO, is determined by the following equation: Av = gm · RO = ICONTROL (mA) × RO 52 (mV) Good linearity can be achieved when controlling over three decades. By connecting Pin 5 to the VCC by way of a resistor, the input is biased at the diode and distortion is reduced. The gain in this case is given by the diode impedance Rd and the ratio of the input resistance RIN, as shown in the following: Av = gm · RO × Rd Rd × RIN (4) Control (Pin 7) This pin controls the differential current. By changing the current which flows into this pin, the gain of the differential amplifier can be changed. (5) Output (Pin 11) The differential amplifier gain (AV) is determined by the resistor RO connected between the output terminal and the Pin 7 control terminal, as follows: Av = gm · RO = ICONTROL (mA) × RO 52 (mV) Make sure the resistor is selected based on the desired maximum output and gain. (6) Buffer input (Pin 12) The buffer input consists of the PNP and NPN emitter follower. The bias current is normally about 0.8µA. Consequently, when used within a small region of control current, we recommend using the high input impedance FET buffer. (7) Buffer output resistance (Pin 14) An 11kΩ resistor is connected between VCC and the output within the IC. When adding an external resistance between the GND and the output, make sure the resistor RL = 33kΩ. The diode impedance Rd = (26 / ID (mA) ) Ω, so that the Pin 5 bias current ID = (VCC - 1V) / R (Pin 5). The graph in Fig. 6 shows the control current in relation to the open loop gain at the diode bias. In the same way, Fig.7 shows the control current in relation to the THD = 0.5% output at the bias point. Fig. 8 shows a graph of the control current in relation to the open gain with no diode bias. Fig. 9 shows a graph of the control current in relation to the SN ratio. Fig. 10 shows a graph of the diode bias current in relation to the SN ratio. Fig. 11 shows a graph of the power supply voltage characteristics. (2) Fig. 4 shows a low pass filter as an example of an application of the BA6110FS. The cutoff frequency fO can be changed by changing the Pin 7 control current. The cutoff frequency fO is expressed as: fO = RA · gm (R + RA) 2πC This is attenuated by -6dB / OCT. Fig. 12 shows a graph of the ICONTROL in relation to the output characteristics. (3) Fig. 5 shows a voltage-controlled secondary low passfilter as an example of an application of the BA6110FS. The cutoff frequency fO can be changed by changing thePin 7 control current. fO = RA · gm (R + RA) · 2πC !Application example (1) Fig.3 shows a voltage-controlled amplifier (AM modulation) as an example of an application of the BA6110FS. This is attenuated by - 12dB / OCT. Fig. 13 shows a graph of the ICONTROL output characteristic. BA6110FS Standard ICs VCC = 15V VIN 150k 5 RIN 10k 1 15 I0 330k 100k VR (Offset adjustment) RIN 10k 3 BA6110FS 7 12 11 9 OUT 14 ICONTROL 30kΩ R0 = 27kΩ VEE = – 15V Fig.3 Voltage-controlled amplifier (electronic volume control) VCC = 15V VIN 20kΩ 7 1 200Ω IC VC 15 100k BA6110FS 3 5 12 11 150pF R 100k 9 14 OUT VEE = – 15V Fig.4 Voltage control low pass filter VCC 15V ICONTROL VC 100kΩ 200 3 11 9 5 100kΩ RA 200Ω R C 100pF VEE 15V RA 200 12 100kΩ 15 1 7 100kΩ 15 1 200Ω 3 11 9 R 5 2C 200pF 12 7 20kΩ VIN BA6110FS 14 BA6110FS 14 V Fig.5 Voltage-controlled secondary low pass filter BA6110FS Standard ICs !Electrical characteristic curves VCC = 15V VEE = – 15V RIN = 10kΩ ID = 200µA 20 10 0 – 10 – 20 – 30 – 40 2 5 10 20 VIN For diode bias of 200µA 10 OUTPUT VOLTAGE: VO (Vrms) OPEN LOOP GAIN: GV (dB) R0 = 50kΩ R0 = 27kΩ OPEN LOOP GAIN: GV (dB) VCC = 15V With diode bias VEE = – 15V RIN = 10kΩ 5 ID = 200µA R0 = 27kΩ fin = 1kHz R0 = 50kΩ 2 Output when THD = 0.5% 1 R0 = 10kΩ VCC = 15V VEE = – 15V RIN = 10kΩ Io = 0 60 50 40 30 20 10 0 No diode bias R0 = 270kΩ R0 = 50kΩ 0.5 0.2 0.1 0.05 0.02 1 2 5 10 20 R0 = 10kΩ ID 200µA + 15V ICONTROL + – R0 = 27kΩ R0 = 10kΩ 10kΩ VO R0 = 27kΩ 15V AV VO VIN 50 100 200 500 1000 50 100 200 5001000 – 10 1 2 5 10 20 50 100 200 500 1000 CONTROL CURRENT: ICONTROL (µA) CONTROL CURRENT: ICONTROL (µA) CONTROL CURRENT: ICONTROL (µA) Fig.6 Open loop gain control current characteristics Fig.7 THD 0.5% output control current characteristics Fig.8 Open loop gain control current characteristics MAXIMUM OUTPUT VOLTAGE: VOM (V) SIGNAL TO NOISE RATIO: S / N (dB) SIGNAL TO NOISE RATIO: S / N (dB) 80 VCC = 15V NOISE B.P.F20 ~ 20kHz SN ratio when THD = 0.5% VEE = – 15V RIN = 10kΩ RO = 27kΩ ID = 200µA fin = 1kHz ICONTROL = 200µA RIN = 50kΩ 80 ICONTROL = 500µA RIN = 10kΩ 70 RIN = 2kΩ VCC = 15V VEE = – 15V RO = 27kΩ fin = 1kHz NOISE B.P.F20Hz ~ 20kHz ICONTROL = 200µA SN ratio when THD = 0.5% 50 100 200 500 1mA 70 IO = 0 60 5 10 20 50 100 200 500 1mA 60 5 10 20 15 12 R0 = ∞ Pin 8 voltage 10 8 6 4 2 0 –2 –4 –6 –8 – 10 – 12 – 14 ±2 ±4 ±6 ±8 VOM VOM ± 10 ± 12 ± 14 CONTROL CURRENT: ICONTROL (µA) BIAS CURRENT: ID (µA) POWER SUPPLY VOLTAGE: VCC (V) Fig.9 SN ratio vs. control current Fig.10 SN ratio vs. diode bias current Fig.11 Maximum output voltage vs. power supply voltage VCC = 15V VEE = – 15V 6pin C = 150pF VOLTAGE GAIN: GV (dB) VCC = 15V VEE = – 15V VOLTAGE GAIN: GV (dB) 0 –4 –8 – 12 – 16 – 20 – 24 – 28 100 200 500 1k 2k ICONTROL = 10µA 6dB / OCT ICONTROL = 100µA 0 –4 –8 – 12 – 16 – 20 – 24 – 28 ICONTROL = 10µA – 12dB / OCT ICONTROL = 100µA 5k 10k 20k 50k 100k 100 200 500 1k 2k 5k 10k 20k 50k 100k FREQUENCY: f (Hz) FREQUENCY: f (Hz) Fig.12 Low pass filter characteristics Fig.13 Secondary low pass filter characteristics BA6110FS Standard ICs !External dimensions (Units : mm) BA6110FS 6.6 ± 0.2 16 9 6.2 ± 0.3 4.4 ± 0.2 1.5 ± 0.1 1 8 0.11 0.8 0.36 ± 0.1 0.3Min. 0.15 SSOP-A16 0.15 ± 0.1