A Novel Design of Monolithic Voltage-Controlled Attenuator Based on E-PHEMT FET

Due to the new features of communications, such as high speed and accurate processing requirements, the AGC (Auto Gain Control) circuit is widely used in the communication apparatus, in which the small volume and high linearity is nessarery and critical factor. As an important part of AGC circuit, a novel voltage-controlled attenuator realized in the form of MMIC is proposed this paper. The attenuator proposed is controlled by a single port. E-PHEMT FET is applied in it to achieve single port positive voltage control function. And linearity function of the voltage-controled attenuation is achieved through optimization of the control circuit aiming for compensation. The MMIC prototype is fabricated by utilizing 0.25μm E-PHEMT process. The size of the chip prototype is 0.9mm×0.9mm. The test results indicate that the electric performance of the proposed attenuator satisfy design targets. The MMIC features smaller volume compared with PIN diode technology, which presents more promising potential for the attenuator design of compact AGC circuit. The proposed voltage-controlled MMIC attenuator is a good candidate for wide application scenarios.