K‐band single balanced mixer for ultra‐wideband radar in 0.18‐μm CMOS technology

Abstract

A K-band single balanced mixer for ultra-wideband radar using a 0.18-m CMOS technology is presented. The designed mixer was applied to LC ladder matching technique on RF port and INTRODUCTIONRegulation approval for an Ultra-Wideband (UWB, 22-29 GHz) by federal communication commission (FCC) in 2002 has attracted the development of millimeter-wave circuits using complementary metal oxide semiconductor (CMOS) process due to low cost and high productivity. Additionally, rapid advance in silicon CMOS technology is becoming possible to make integrated circuits above 20-GHz frequency band such as a K-band low noise amplifier [1], a 24-GHz voltage controlled oscillator [2], and a 24-GHz mixer [3]. Especially, many downconversion microwave mixers which are one of the most fundamental circuit components were published, for example, a 24-GHz RF front-end including low noise amplifier and mixer [3] and a K-band single balanced mixer with high P1dB compression [6]. The mixers [3-6] based on Gilbert-type which offers good port to port isolation, medium noise figure, and high gain, achieved reasonable performances for gain, isolation, and linearity. However, the shortage of accurate CMOS passive models above 20-GHz frequency still makes it difficult to design wideband mixers for 24-GHz automotive radar applications. To obtain the range resolution of 10 cm, bandwidth is required 1.5 GHz in a pulsed radar system.A K-band down conversion mixer was presented 1.4-GHz bandwidth with 0.13-m CMOS technology in 2005 [7], but it has limitation for low radio frequency (RF) of 19 GHz. Published papers using 0.18-m CMOS technology also showed 3-dB bandwidth about 1 GHz [3, 6]. In this article, a K-band single balanced mixer for ultra-wideband radars, which down converts RF signal of 23.4 -24.8 GHz to 100-MHz intermediate frequency (IF), is designed and measured in 0.18-m CMOS technology. The mixer is designed the specification of 1.5-GHz bandwidth to obtain range resolution of 10 cm. The designed mixer shows the performances of wide bandwidth, high linearity, reasonable power conversion gain, and low supply voltage. CONFIGURATION AND DESIGNThe proposed mixer is fabricated on the silicon substrate with dielectric constant of 11.9 and thickness of 300 m in the 0.18-m TSMC (CMOS) process. This process provides six metals (M1-M6) and one poly layer. A top metal of 2.3-m thick is used for signal line and spiral inductors due to low loss. Provided MIM (metal insulator metal) capacitors consist of Metals 4 -6 and CTM (capacitor top metal). They are used for matching network, DC blocking, and bypass. Poly resistors are available for bias circuit and IF matching network. All passive devices are simulated using the 3D electromagnetic simulator, HFSS, and measured up to 40 GHz using HP 8510C network analyzer for millimeter-wave operation. The proposed single balanced mixer was designed to obtain wide bandwidth performance for automotive radar applications. Figure 1 shows the circuit schematic of the designed single balanced mixer, which r...

Bandwidth enhancement of K‐band CMOS mixer using balun matching for UWB radar

“…Figure 6 shows the input 1 dB compression point (input P1dB), which is Ϫ4 dBm. The comparison of the designed mixer with the one in [5], [7], and [8] is shown in Table 1.…”

“…A single balanced mixer with LNA and a double balanced mixer with 0.3-25 GHz ultrawide band were published in [5] and [6], respectively. In addition, the CMOS mixers for automotive radar applications were presented in [7] and [8]. A single balanced mixer in [7] presented a conversion gain of 1.2 dB.…”

“…In addition, the CMOS mixers for automotive radar applications were presented in [7] and [8]. A single balanced mixer in [7] presented a conversion gain of 1.2 dB. A double balanced mixer in [8] showed a conversion gain of 1 dB.…”

“…A double balanced mixer in [8] showed a conversion gain of 1 dB. However, these mixers revealed disadvantages such as complex matching circuits [7] and operating frequency limitation with a RF signal of 19 GHz [8]. Both of them also have a 1.4 GHz bandwidth limitation.…”