Page 84 - Op Amps Design, Applications, and Troubleshooting

Noninverting Amplifier 67

0.5 V/fJs
3.14 x 155 kHz
= 1.03 V peak-to-peak

Power Supply Rejection Ratio. The power supply rejection ratio provides
us with an indication of the degree of immunity the circuit has to noise voltages
on the DC power lines. The change in output voltage (v 0) for a given change in DC
power line noise voltage (V N) is computed with Equation (2.23):

where v 0r V N, R F, R ;, and PSRR are the values of the output noise signal, the noise
signal on the DC supply lines, the feedback resistor, the input resistor, and the
power supply rejection ratio (PSRR), respectively. The manufacturer's data sheet
in Appendix 1 lists the PSRR as ranging from 30 to 150 microvolts per volt. The
worst-case effect on the output voltage for the circuit in Figure 2.12 is then

= V N x 0.000968

In other words, the amplitude of the power line noise (V N) will be reduced by a fac-
tor of 0.000968. This means, for example, that if the DC supply lines had noise sig-
nals of 100 millivolts peak-to-peak, we could anticipate a similar signal in the
output with an amplitude of about

2.3.3 Practical Design Techniques
The following design procedures will enable you to design noninverting op amp
circuits for many applications. Although certain nonideal considerations are
included in the design method, additional nonideal characteristics are described
in Chapter 10.
To begin the design process, you must determine the following requirements
based on the intended application:

1. Voltage gain
2. Frequency range