Direct multilevel carrier modulation using millimeter-wave balanced vector modulators

Abstract

The importance of being able to design affordable, high-performance, millimeter-wave transmitters for digital communications and radar applications is increasing. To this end, two monolithic millimeter-wave vector modulators have been realized at 38 and 60 GHz for use in direct multilevel carrier modulation. It is shown that, by employing balanced biphase amplitude modulator elements, accurate constellations are achieved with broad-band operation from 20 to 40 GHz and 55 to 65 GHz. Modulations of 16-and 256-QAM have been demonstrated, both at 38 and 60 GHz, using this technique. Each balanced biphase amplitude modulator uses a pair of reflection-type attenuators operated in push-pull mode. This study investigates the suitability of this topology for use as a full biphase amplitude modulator for multilevel digital modulation schemes. It is found that the technique is very robust and the resulting analog vector modulator can be a very important component for many future millimeter-wave applications.

A balanced reflection type HMIC vector modulator over 34–36GHz based on cold state pHEMTs

“…The value of them should satisfy equation (1) to reduce insertion loss. The transmission coefficient S21 of such balanced bi-phase attenuator can be determined by equation (2) as stated in reference [2]. (1)…”

A novel broadband MMIC vector modulator for V-band applications

“…The resulting BM die, 1.8 Â 1 mm 2 in size, has been designed to operate from 45 to 65 GHz band; a microphotograph is depicted in Figure 11. Other VMs have been designed to operate in this band such as [9] and [10]. The band around 60 GHz has been selected since, due to a high atmospheric absorption, it is suitable for short-range radio communication applications.…”

“…The [Y] matrix (Y FET ) representation of the intrinsic part of a FET device is reported in (8). Inserting the matrix elements in (9) and considering the external gate resistor R G connected in parallel with the gate, by substituting the resulting Y LOAD in (10), an approximated expression for the reflection coefficient C LOAD of the load is obtained.…”

“…To solve the problem, two main strategies are possible: the first one, reported in [18], is based on direct parasitics compensation, being therefore suitable for narrowband applications only; the second one is the balancing technique, mostly used for broadband applications [9][10][11][12][13][14][15][16][17].…”

“…In particular, four 90 deg couplers (Lange Couplers) are typically adopted, leading to an overall number of nine couplers for a complete VM scheme, composed by two BMs. Despite some realizations have been presented, also in monolithic form [9][10][11][12][13][14][15][16][17], a different implementation approach is highly desirable, leading to an improvement in circuit size and sensitivity. In this article, a novel VM topology is presented, based on the combination of two BMs, whose operating mechanism is based on the balanced load principle.…”