A highly linear double balanced Schottky diode S-band mixer

In this paper, we propose a double balanced mixer with a tunable Marchand balun. The circuit is designed in a SiGe BiCMOS process using Schottky diodes. The tunability of the Marchand balun is used to enhance critical parameters for double balanced mixers. The local oscillator-IF isolation can be changed from -51 to -60.5 dB by tuning. Similarly, the IIP 2 can be improved from 41.3 to 48.7 dBm at 11 GHz, while the input referred 1-dB compression point is kept constant at 8 dBm. The tuning have no influence on conversion loss, which remains at 8.8 dB at a LO power level of 11 dBm at the center frequency of 11 GHz. The mixer has a 3 dB bandwidth from 8 to 13 GHz, covering the entire X-band. The full mixer has a size of 2050 mm × 1000 mm. . This overcomes the problem with image frequency channel and leaves only the desired signal, directly at baseband. Mixers for direct conversion are also used in Doppler radars, as the direct conversion architecture gives the Doppler shift directly from the received frequency. Mixers for direct conversion have the drawback that the radio frequency (RF) and local oscillator (LO) frequencies are at the same frequency, thus good isolation between the ports is important as filtering is not possible. Also, as the output frequency is low, flicker or 1/f noise might be a problem.The double balanced mixer ideally provides infinite isolation between all ports and is therefore a good choice to use as a mixer for direct conversion. Other benefits of the double balanced mixer are rejection of LO noise and high linearity [2]. The balancing circuits should, to get full benefit of the double balanced architecture, be well adjusted. This is challenging to achieve in practice due to process and manufacturing variances.To utilize the broadband nature of the double balanced mixer, the balun should also be broadband otherwise the bandwidth of the mixer will be limited. The Marchand balun [3] is in itself very broadband, and it is commonly used for this reason in a planar [4][5][6] or lumped-distributed [7][8][9] implementation. In [10] we presented a Marchand balun with tunable phase balance, and in [11, 12] we presented a broad band double balanced mixer using diode connected heterojunction bipolar transistors (HBTs) together with lumped Marchand baluns on RF and LO ports. The mixer design presented here integrates the tunable Marchand balun on the LO-port together with Schottky diodes for the mixing core. This allows to correct for any mismatches either in the balun design or in the mixing core itself. This should then enhance the benefits of practical implementations of double balanced mixers, where our focus will be on the properties important for direct conversion mixing, i.e. port isolation and linearity. To the author's knowledge a double balanced ring mixer with balance corrections using a tunable balun is demonstrated here for the first time. I I . D E S I G N O F M I X E R W I T H T U N A B L E B A L U NThis section gives a description of the design of the circuitry. First a description ...

show abstract

“…The best IIP2 is achieved by [11], but after tuning our circuit is close to this and on par with [17].…”

Section: Resultssupporting

confidence: 64%

“…Of course, the active topology comes with the benefit of having 4.5 dB gain compared with 28.8 dB or worse for the passive diode-based topologies. The 1 dB compression point is lower than what is reported for [17] and [11], but these also exhibit more loss.…”

Section: B) Full Mixer Circuitcontrasting

confidence: 68%

An X-band Schottky diode mixer in SiGe technology with tunable Marchand balun

Michaelsen

Johansen

Tamborg³

et al. 2016

Int. J. Microw. Wireless Technol.

View full text Add to dashboard Cite

show abstract

“…A third-order intermodulation intercept (IIP3) of 13.8 dBm is achieved in these devices with an LO input power (P LO ) of 0 dBm, resulting in a quality factor of Q IIP3 = IIP3/P LO = 13.8 dB. Conventional diode or single-transistor mixers often have quality factor between 5 and 30 dB at GHz [12], [13].…”

Section: Graphene Ambipolar Mixersmentioning

confidence: 99%

Graphene-Based Ambipolar RF Mixers

Wang

Hsu

et al. 2010

IEEE Electron Device Lett.

244

155

View full text Add to dashboard Cite

“…These compression levels are comparable to what has been achieved in GaAs [5, 6] and even in SiGe HBT technology [7], with diode quad ring mixers. In the wide band-gap semiconductor material silicon-carbide (SiC) mixers have been presented with higher input-power compression point, but at the same time requiring a large LO power, such as in [8], with a P1dBin of 23 dBm at 24 dBm LO power.…”

Section: Introductionmentioning

confidence: 99%

6–12 GHz double-balanced image-reject mixer MMIC in 0.25 µm AlGaN/GaN technology

Heijningen¹,

Hoogland²,

Hek³

et al. 2015

Int. J. Microw. Wireless Technol.

View full text Add to dashboard Cite

The front-end circuitry of transceiver modules is slowly being updated from GaAs-based monolithic microwave integrated circuits (MMICs) to Gallium-Nitride (GaN). Especially GaN power amplifiers and T/R switches, but also low-noise amplifiers (LNAs), offer significant performance improvement over GaAs components. Therefore it is interesting to also explore the possible advantages of a GaN mixer to enable a fully GaN-based front-end. In this paper, the design-experiment and measurement results of a double-balanced image-reject mixer MMIC in 0.25 μm AlGaN/GaN technology are presented. First an introduction is given on the selection and dimensioning of the mixer core, in relation to the linearity and conversion loss. At the intermediate frequency (IF)-side of the mixer, an active balun has been used to compensate partly for the loss of the mixer. An on-chip local-oscillator (LO) signal amplifier has been incorporated so that the mixer can function with 0 dBm LO input power. After the discussion of the circuit design the measurement results are presented. The performance of the mixer core and passive elements has been demonstrated by measurements on a test-structure. The mixer MMIC measured conversion loss is <8 dB from 6 to 12 GHz, at 1 GHz IF and 0 dBm LO power. The measured image rejection is better than 30 dB.

show abstract

A highly linear double balanced Schottky diode S-band mixer

Cited by 17 publications

References 8 publications

An X-band Schottky diode mixer in SiGe technology with tunable Marchand balun

An X-band Schottky diode mixer in SiGe technology with tunable Marchand balun

Graphene-Based Ambipolar RF Mixers

6–12 GHz double-balanced image-reject mixer MMIC in 0.25 µm AlGaN/GaN technology

Contact Info

Product

Resources

About