4-Bit Ka Band Sige Bicmos Digital Step Attenuator

Abstract

Abstract-This paper presents a Ka-band 4-bit BiCMOS digital step attenuator with maximum attenuation of 7.5 dB (16 states). The proposed attenuator design is based on switched T-bridge network including phase correction network and is fabricated in 0.13 µm SiGe BiCMOS technology. Attenuator with phase correction structure shows root mean square (RMS) amplitude errors < 0.8 dB at 31 to 33 GHz and the RMS insertion phase varying from 2.8 • to 5.8 • over 31-33 GHz. The measured insertion loss is 19 dB and total chip size including pad is 1.92 × 0.4 mm 2 .

A 6-Bit 0.13 μm SiGe BiCMOS Digital Step Attenuator with Low Phase Variation for K-Band Applications

“…Note that for larger attenuations, we have adopted Pi configuration, whereas Bridged-T configuration is chosen for smaller ones, as depicted in Figure 9. Conversely, the 4-bit attenuator merely exploits the bridge-T type attenuator [18]. Furthermore, the 6-bit attenuator which is an extension of our previous work is to implement a higher bit mm-Wave digital step attenuator on silicon-based technology.…”

“…We believe a low pass filter, with phase lag characteristics can be used to minimize the transmission phase difference [4,17,18], which essentially depends on series capacitances Ca and Cb of the proposed phase correction network within the π-type attenuator, shown in Figure 5. It is important to satisfy Equation (2) in order to minimize the phase difference between the attenuator's two states, where ∅ R is the transmission phase at reference state and ∅ A is the transmission phase at attenuation state [17].…”

“…We believe a low pass filter, with phase lag characteristics can be used to minimize the transmission phase difference [4,17,18], which essentially depends on series capacitances Ca and Cb of the proposed phase correction network within the π-type attenuator, shown in Figure 5. Figure 6a presents behavior of the phase difference in response to variations in the two capacitances, between 0 and 130 fF.…”

“…Note that parts (a) and (b) of the figure show the reference and attenuation states, respectively. The proposed model of a 6-bit digital step attenuator is an extended version of our previously designed 4-bit digital step attenuator, simulated in the range of 31-33 GHz [18]. In contrast, the 6-bit attenuator is designed for systems that require higher attenuation, i.e., 31.5 dB with a minimum phase error, and is simulated in the range of 20-24 GHz, consisting of 64 attenuation states and cascaded in the sequence of 8, 2, 1, 0.5, 4 and 16 dB, as shown in Figure 8.…”

“…The measurement results show that the proposed designed attenuator can be efficiently used for K-band applications, having the frequency range of 20-24 GHz for a controlled amplitude and phase. Table 2 compares the performance of attenuators reported in the most recently published articles [6,8,9,12,[17][18][19]. Compared with the GaAs attenuators [6,8,9,12], the proposed attenuator has the highest attenuation of 31.5 dB and the best resolution of 0.5 dB.…”