The output of the oscillator is AC coupled via C1 to the DUT noninverting (NI) amplifier circuit. For the dual op amp case, one of the op amps is configured as above (NI gain of 11),Īnd the output is connected directly to the second half as a unity gain follower.
The circuit can be easily configured to test both standard single op amps and DUAL op amps withĪ convenient slider switch functionality. The oscillator output level can also be increased to check op amps with R-RĬapability or to verify the limits of the output level against the supply voltage.Īny standard op amp specified as being stable in a gain of 10 or less can be tested with this circuit.Īlso, at 22 kHz, the required slew-rate for this output level is a low 0.5 V/us and is therefore suitable for testingĪlmost all op amps. Of all op amps operating from a +/- 6V supply. This is within the voltage output drive capability The expected peak op amp output is about 3.3V for the 300 mV input level. The device under test (DUT) is configured as a standard non-inverting voltage amplifier with a signal gain of 11 with Without an oscilloscope but with a typical digital multimeter which usually has AC voltage frequency response up to a few kHz. At a lower frequency, the test circuit can be used The components of the oscillator can be easily changed for frequencies from hundreds of Hz to about 500 kHz.įor example, to operate at 1 kHz, substitute Rw = 1.5 kohm and Cw = 0.1 uF. This is useful during offset voltage monitoring as it eliminatesĪny oscillator background coupled noise on the protoboard. Switch Sw1 is added to disable the Wien-bridge oscillator. The Radj pot is used toĪdjust the oscillator output level to about 300 mV before buffering with the second amplifier in the dual. The oscillator uses a dual LM4562 op amp with a GBW of 50 MHz and a slew rate of 20 V/us. The circuit uses a classic low distortion Wien-bridge oscillator configured to run at 22 kHz. The circuit has been found useful for checking
OP AMP OFFSET CANCELLATION PORTABLE
The test circuit can be powered by a portable dual 6V DC battery supply.
Component values facilitate checking offset voltage and bias current values. The design uses a non-inverting op amp circuit configuration suitable forīasic test purposes. The circuit includes a 22 kHz Wien-bridge This article presents a simple implementation of a compact convenient portable test circuit which can be used withĪ low bandwidth oscilloscope to quickly check any standard voltage feedback op amp with standard pin outs.
0 kommentar(er)
