Verifying Rollett’s Proviso on Active Devices Under Arbitrary Passive Embeddings

Colangeli, Sergio; Ciccognani, Walter; Palomba, Mirko; Limiti, Ernesto

doi:10.1109/tcsii.2016.2642401

Cited by 9 publications

(7 citation statements)

References 16 publications

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“…If the first provision of unconditional stability is established for the Y matrix, that is Y has stable elements (known as intrinsic stability), and

normalR normale ([], y_{i i} (j ω)) > 0 \forall ω ⩾ 0 normala normaln normald i = 1, 2,

where ω is the angular frequency, then Δ u has no RHP zeros and is unconditionally stable. The intrinsic stability of Y can be investigated by statistical analysis [14]. Equation () can be rewritten as

normalΔ = {normalΔ}_{u} ((), 1 + \frac{y_{12} {normalΔ}_{y 12}}{{normalΔ}_{u}}) = {normalΔ}_{u} normalN normalD normalF .

…”

Section: Stability Analysismentioning

confidence: 99%

“…Numerous treatments addressing the instability issue are provided in the literature [2][3][4][5][6][7][8][9][10][11][12][13][14]. Linville or μ-factors are useful implements for checking the conditional stability of a linear two-port network which is intrinsically stable [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…The open-loop approach in [12][13][14][15][16] originates from the concept of return ratio, introduced by Bode [11]. This approach is utilised in literature [12] as the concept of NDF for analysing the stability statues of multi-loop linear circuits.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stabilisation of multi‐loop amplifiers using circuit‐based two‐port models stability analysis

Pasdar

Meghdadi

Medi

2021

IET Circuits, Devices & Syst

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This article applies a systematic approach based on the normalized determinant function (NDF) theory to analyse stability in multi‐loop circuits and to design the required stabilization network. Presenting several provisions, the return ratios are extracted by employing immittance or hybrid matrices (Z, Y, G or H) of active two ports. Using these matrices, instead of the S‐parameters, facilitates the selection of an appropriate stabilizer network. As a practical case, a non‐uniform distributed amplifier (NDA) is designed and inspected for potential instabilities. The presented procedure detects instability associated with one of the NDA circuit's loops, and an appropriate stabilization circuit is accordingly devised. In order to validate the procedure, the designed NDA is implemented in a 0.1‐μm GaAs pHEMT process. As predicted, the measurements show oscillations, once the on‐chip stabilization circuit is disabled.

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“…If the first provision of unconditional stability is established for the Y matrix, that is Y has stable elements (known as intrinsic stability), and

normalR normale ([], y_{i i} (j ω)) > 0 \forall ω ⩾ 0 normala normaln normald i = 1, 2,

normalΔ = {normalΔ}_{u} ((), 1 + \frac{y_{12} {normalΔ}_{y 12}}{{normalΔ}_{u}}) = {normalΔ}_{u} normalN normalD normalF .

…”

Section: Stability Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stabilisation of multi‐loop amplifiers using circuit‐based two‐port models stability analysis

Pasdar

Meghdadi

Medi

2021

IET Circuits, Devices & Syst

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“…The technique adopted to justify this specific form of the Ohtomo test can be found in Ref. . No instabilities were found in the realized amplifiers.…”

Section: Stacked Lna Designmentioning

confidence: 99%

Three‐stage GaN‐on‐SiC medium‐power LNA exploiting a current‐reuse architecture

Colangeli

Vittori

Ciccognani

et al. 2018

Int J RF Microw Comput Aided Eng

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A recently presented implementation of the current‐reuse concept, specifically devised for microwave cascaded single‐ended amplifiers, is applied to the design of a three‐stage medium‐power low‐noise amplifier (LNA) operating in X‐band. The LNA is realized on a GaN‐on‐SiC 0.25 µm technology supplied by Leonardo S.p.A.'s internal foundry and achieves a transducer gain (GT) of 24 dB, a noise figure (NF) better than 2.5 dB and an output power at 1 dB gain compression (Pout,1dB) higher than 20 dBm over the whole X‐band. The first two stages of the LNA are stacked and share the same current while requiring, as a pair, a doubled external supply voltage, which corresponds to that of the third, medium‐power stage. The versatility of the adopted current‐reuse concept is exemplified by the fact that the two low‐noise stages are initially designed in a conventional single‐ended topology: only in a second step are they converted into a current‐sharing stage pair with no significant effect on RF performance. Nonconventional approaches to low‐noise design and small‐signal stability analysis developed by the Authors and adopted in this design are referred to the Reader.

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“…Devices exhibiting layout symmetry are frequently analysed using the eigenvalue analysis [14] and by splitting the circuit and enforcing a ground connection at the power combining port [15]. More general approaches that are not constrained to symmetrical circuits are the normalized determinant function (NDF) [16], [17] and Ohtomo test [18], [19]. The main limitation of the aforementioned odd-mode stability analysis techniques is their inapplicability to devices operating in the non-linear regime, with the fundamental limitation arising from the derivation of the linear stability analysis techniques, which is based on the linearisation of the device around its DC operating point.…”

Section: Introductionmentioning

confidence: 99%

Direct ${E}$ -Field Measurement and Imaging of Oscillations Within Power Amplifiers

Urbonas

Kim

Aaen

2019

IEEE Trans. Instrum. Meas.

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We present for the first time a measurement system that is capable of directly detecting and identifying the physical location of an oscillation within RF and microwave power amplifiers. The method uses a combined external electrooptic, non-linear vector network analyzer, and vector load-pull measurement system, which allows the measurement of crossfrequency phase-coherent multi-harmonic vector electric fields above the transistor with an 8 µm spatial resolution and 20 MHz-40 GHz bandwidth. Raster scans above the amplifier allow the time-domain electric fields to be animated and superimposed on top of the amplifier image enabling immediate identification of any oscillations by direct inspection. The method is first demonstrated on a low power amplifier composed of two parallel 0.1-W pHEMT transistors that is intentionally designed to have an odd-mode oscillation. The applicability of the method is further demonstrated by measuring and animating in-package parametric odd-mode oscillations within a 260-W laterally diffused metal-oxide-semiconductor (LDMOS) transistor operating at 2.2 GHz under pulsed RF conditions with 10 µs pulses and 10% duty cycle. The measurement and identification technique is applicable to all semiconductor devices as the external electric field is non-invasively measured above the amplifier.

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Verifying Rollett’s Proviso on Active Devices Under Arbitrary Passive Embeddings

Cited by 9 publications

References 16 publications

Stabilisation of multi‐loop amplifiers using circuit‐based two‐port models stability analysis

Stabilisation of multi‐loop amplifiers using circuit‐based two‐port models stability analysis

Three‐stage GaN‐on‐SiC medium‐power LNA exploiting a current‐reuse architecture

Direct ${E}$ -Field Measurement and Imaging of Oscillations Within Power Amplifiers

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