A C/X/Ku/K-Band Precision Compact 6-Bit Digital Attenuator with Logic Control Circuits

Abstract

This paper proposes a C/X/Ku/K band 6-bit digital step attenuator (DSA) which employs a variety of improved attenuation cells to achieve a wide bandwidth, stable amplitude variation, stable phase variation, and small area. In this paper, the improved T-type, π-type, and switched-path type topologies are analyzed theoretically and applied to different attenuation values to achieve the optimal attenuator performance. In addition, in order to reduce the complexity and to improve the stability of the overall radar system, the logic control circuit is integrated in the DSA chip in this paper. Finally, the proposed attenuator is implemented in 0.15μm GaAs technology, which has a maximum attenuation range of 31.5 dB with 0.5 dB steps. The proposed DSA exhibits a root-mean-square (RMS) attenuation error of less than 0.15 dB and an RMS phase error of less than 3°, at 4–24 GHz. The insertion loss (IL) and the area of the DSA are 4.3–4.5 dB and 1.5 mm × 0.4 mm, respectively. Benefiting from the improvements of the attenuation cells and the characteristic of GaAs technology with strong resistance to radiation and power processing capability, the proposed DSA is suitable for spaceborne radar systems.

An X-Band High-Accuracy GaAs Multifunction Chip With Amplitude and Phase Control

“…It can be seen that a suitable Cp can remarkably improve the ISP. The tuning methods for these topologies can be found in previous work [10].…”

“…High accuracy is required for MFCs used in phased arrays, but it is a challenge due to the large scale of the circuit. There are many studies on ATTs and PSs in [10]- [16], and they all exhibit excellent attenuation and phase shift accuracy. However, cascading between blocks in the MFC changes the terminal impedances of the ATT and PS, causing deterioration in accuracy.…”

Design of a 9kHz-6GHz Dual-Channel Switch Attenuator Chip

“…The switch is an important component of the attenuator network, and its microwave performance directly determines the overall performance of the attenuator network. The switch device can be considered as a device that controls the signal connection and disconnection [9]. In this design, we can treat the attenuator channel/through-channel as an equivalent two-port network, and the insertion loss and isolation can be regarded as the S-parameters of the two-port network [10].…”

“…The chip size was small, but it had the issue of relatively large insertion loss. In the same year, Jialong Zeng et al used 0.15um GaAs pHEMT to design a 6-bit attenuator in the 4-24GHz frequency range [9], with a return loss greater than 18dB and high attenuation accuracy, but it also had the problem of relatively large insertion loss.…”