I might have the TINA program but I never tried it.
My peak detector is simple:
1) the opamp has a very high input resistance, a very low output resistance and a voltage gain of exactly 1.
2) When the input to the opamp is 0V then the voltage of the capacitor is also 0V because the diodes are the same.
3) When the input increases its voltage then the capacitor is charged to the same voltage by the 10k resistor.
4) When the input goes negative then the capacitor slowly discharges into the 1M resistor because the second diode is reverse-biased.
5) When the input suddenly drops to 0V after a peak that charged the capacitor then the capacitor slowly discharges into the 1M resistor because the second diode is reverse-biased.