0.1

100

100k

10

100

1000

10000

1k

10

1M

FREQUENCY (Hz)

10k

1

VS = 5V

LMP2014MT

www.ti.com

SNOSAK6B – DECEMBER 2004 – REVISED MARCH 2013

MORE BENEFITS

The LMP2014 offers the benefits mentioned above and more. It has a rail-to-rail output and consumes only 950

µA of supply current while providing excellent DC and AC electrical performance. In DC performance, the

LMP2014 achieves 130 dB of CMRR, 120 dB of PSRR and 130 dB of open loop gain. In AC performance, the

LMP2014 provides 3 MHz of gain-bandwidth product and 4 V/µs of slew rate.

HOW THE LMP2014 WORKS

The LMP2014 uses new, patented techniques to achieve the high DC accuracy traditionally associated with

chopper-stabilized amplifiers without the major drawbacks produced by chopping. The LMP2014 continuously

monitors the input offset and corrects this error. The conventional chopping process produces many mixing

products, both sums and differences, between the chopping frequency and the incoming signal frequency. This

mixing causes large amounts of distortion, particularly when the signal frequency approaches the chopping

frequency. Even without an incoming signal, the chopper harmonics mix with each other to produce even more

trash. If this sounds unlikely or difficult to understand, look at the plot (Figure 30), of the output of a typical

(MAX432) chopper-stabilized op amp. This is the output when there is no incoming signal, just the amplifier in a

gain of -10 with the input grounded. The chopper is operating at about 150 Hz; the rest is mixing products. Add

an input signal and the noise gets much worse. Compare this plot with Figure 31 of the LMP2014. This data was

taken under the exact same conditions. The auto-zero action is visible at about 30 kHz but note the absence of

mixing products at other frequencies. As a result, the LMP2014 has very low distortion of 0.02% and very low

mixing products.

Figure 30.

Figure 31.

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