An amplifier that is designed to operate only with a very narrow range of input frequencies. A typical frequency response curve is shown in Fig. a. The response may be modified to give an essentially flat response to the frequencies in the pass band by using stagger tuning. A stagger tuned amplifier consists of two or more amplifier stages each of which is tuned to slightly different frequencies, f₁ and f₂. The overall response is essentially flat within the pass band (Fig. b), the centre of the peak occurring at the frequency corresponding to

(a) Frequency response of a tuned amplifier (b) Response of a stagger tuned amplifier