High power efficiency distributed oscillator based on composite-right-/left-handed unit cells

Abstract

A microwave oscillator topology based on CRLH (Composite Right-/Left-Handed) unit cells is\ud analyzed theoretically and experimentally tested. The oscillator consists of a CRLH based\ud distributed amplifier and a positive feedback realized by a simple transmission line. The oscillator\ud has two output ports, where the power levels are practically the same. For this topology, we have\ud found the oscillation condition and we demonstrate that each transistor gives the same contribution\ud to the power delivered at the two output ports, in this way, the output power is maximized. The\ud oscillator has been designed for a frequency of oscillation of 2.8 GHz and fabricated in hybrid\ud technology, by using InGaAs HEMTs and microstrip lines. The measured powers at the two output\ud ports are equal to 12.6 dBm and 10.4 dBm, the small difference between these values being given\ud by the insertion loss of the gate line. The experimental frequency of oscillation is 2.77 GHz, with a\ud difference of less than 1% in comparison with the expected value. Due to the frequency selectivity\ud of the CRLH unit cells, numerical simulations predict low phase noise for this configuration of\ud oscillator.

Power Performance and Spurious Frequencies Analysis of Composite Right-/Left-Handed (Crlh) Distributed Oscillators

“…A uniform transmission line with characteristic impedance Z 0 and electrical length ϕ is used to realize the FTL component. In [12], it has been demonstrated that for having oscillations, the following condition must be fulfilled:…”

“…The output ports of the gate and drain lines are loaded by the impedance Z 0 , and FTL is a positive feedback element consisting of a transmission line. In this circuit, each transistor supplies nearly the same amount of power, as demonstrated in [12]. This advantage cannot be obtained by using the conventional low-pass unit cells reported in [6,10,11].…”

“…Starting from [1], a number of papers have been published on distributed oscillators [6][7][8][9][10][11]. In a recent letter [12], a significant innovation has been proposed, replacing the low-pass network of the unit cell, with a CRLH (Composite Right-/Left-Handed) topology, as shown in Fig. 1(a).…”

“…The organization of this paper is as follows. In Section 2, the design of the CRLH double output distributed oscillator, briefly discussed in [12], is presented more in detail. Section 3 concerns the transformation of this circuit in a single output signal generator.…”

A Design Oriented Linear Model for CRLH Distributed Oscillators

“…The basic principle of this circuit has been also applied to other components, such as active dividers [5][6][7], frequency doublers [8][9][10], phase shifters [11][12][13][14][15], and oscillators [16][17][18][19][20]. For the latter ones the conventional configuration has been recently modified, replacing the low pass unit cell by a Composite Right-/Left-Handed (CRLH) topology [21,22]. The conceptual configuration of this oscillator is shown in Fig.…”