ZHCSGM4C August 2017 – October 2023 OPA838
PRODUCTION DATA
The OPA838 can be used as an inverting amplifier with signal input to the inverting input (VIN–) through the gain-setting resistor (RG.) Figure 8-2 illustrates a basic block diagram of the circuit.
If VIN = VREF + VSIG, and the noninverting input is dc biased to VREF, the output of the amplifier is calculated according to Equation 2:
The signal gain of the circuit and VREF provides a reference point around which the input and output signals swing. For bipolar-supply operation, VREF is often GND. The output signal is 180° out-of-phase with the input signal in the pass band of the application. Figure 9-2 illustrates the 50-Ω input matched configuration used for the inverting characterization plots. In this case, an added termination resistor is placed in parallel with the input RG resistor to provide an impedance match to 50-Ω test equipment. Table 9-2 lists the suggested values for RF, RG, and RT for inverting gains from –6 V/V to –20 V/V.
AVERAGE | RF (Ω) | RG (Ω) | EXACT RT | STANDARD RT | INPUT ZI | ACTUAL (V/V) | GAIN (dB) |
---|---|---|---|---|---|---|---|
–6 | 1180 | 196 | 67.1 | 66.5 | 49.7 | –6.02 | 15.59 |
–7 | 1370 | 196 | 67.1 | 66.5 | 49.7 | –6.99 | 16.89 |
–8 | 1540 | 191 | 67.7 | 68.1 | 50.2 | –8.06 | 18.13 |
–9 | 1690 | 187 | 68.2 | 68.1 | 49.9 | –9.04 | 19.12 |
–10 | 1870 | 187 | 68.2 | 68.1 | 49.9 | –10 | 20 |
–11 | 2050 | 187 | 68.2 | 68.1 | 49.9 | –10.96 | 20.80 |
–12 | 2210 | 182 | 68.9 | 68.1 | 49.6 | –12.14 | 21.69 |
–13 | 2370 | 182 | 68.9 | 68.1 | 49.6 | –13.02 | 22.29 |
–14 | 2550 | 182 | 68.9 | 68.1 | 49.6 | –14.01 | 22.93 |
–15 | 2740 | 182 | 68.9 | 68.1 | 49.6 | –15.05 | 23.55 |
–16 | 2870 | 178 | 69.5 | 69.8 | 50.1 | –16.12 | 24.15 |
–17 | 3090 | 182 | 68.9 | 69.8 | 50.5 | –16.98 | 24.6 |
–18 | 3240 | 178 | 69.5 | 69.8 | 50.1 | –18.20 | 25.2 |
–19 | 3400 | 178 | 69.5 | 69.8 | 50.1 | –19.10 | 25.62 |
–20 | 3570 | 178 | 69.5 | 69.8 | 50.1 | –20.06 | 26.04 |