Design and Realization of Trunk Amplifier at 2.5–2.6 GHz

In view of the difficulty of gain control and the problem of self-excitation, a trunk amplifier with automatic gain control and anti-self-excitation is proposed. The system has a high operating frequency, with an uplink operating frequency band of 2500–2570 MHz, a downlink operating band frequency of 2620–2690 MHz, a downlink gain of 45 dB, an uplink gain of 55 dB, a passband ripple of less than 6 dB, a noise coefficient of less than 6 dB, and a voltage standing wave ratio (VSWR) of less than 2. We introduce the main circuits of the system, which includes low-noise amplifier (LNA) circuit, power drive amplifier circuit, power amplifier (PA) circuit, automatic gain control (AGC) circuit, and surface acoustic filter (SAW) circuit. Then, we carried out production and testing of the system. The test results show that the system basically meets the expected requirements. At the same time, it has the characteristics of low cost, controllable gain, and anti-self-excitation. It has great advantages in reducing operation and maintenance costs.