ZHCSIQ4B September 2018 – December 2018 OPA828
The parameters of an amplifier the best describes the small signal dynamic behaviour are the gain-bandwidth product (GBP), unity gain frequency (UGF) and phase margin (PM) of an amplifier. The GBP is a useful parameter to determine the bandwidth of an application in closed loop configurations. Equation 3 can be used to approximate the closed loop bandwidth for the OPA828. Typically the GBP is a specified parameter with the amplifier configured in a non-inverting gain of 100 (40 dB). The GBP of an amplifier is generally assumed to be constant over frequency but in some higher speed amplifiers this is not always the case. The OPA828 has a constant GBP all the way to its UGF, as such the OPA828 open-loop gain has a constant –20 dB/decade slope (–6 dB/octave). The UGF is defined as the frequency at which the gain of the amplifier crosses 1V/V (0 dB). Figure 53 Illustrates the concept of GBP and UGF. The OPA828 has both a GBP and UGF of 45 MHz.