| 1. |
- Rohner, M., et al.
(författare)
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Sub-f(t) gain resonance of InP/InGaAs-HBTs
- 2002
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383 .- 1557-9646. ; 49:2, s. 213-220
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Tidskriftsartikel (refereegranskat)abstract
- Advanced npn-InP/InGaAs HBTs are often operated at high current levels for optimum high-speed performance. Because of velocity modulation effects, these transistors may operate in base-pushout although measurements of the cut-off frequency f(t) indicate the opposite. We show that the low mobility of the holes has a strong effect on the transistor operation in this regime, which is only revealed from a dynamic analysis: The unilateral power gain peaks far below f(t) followed by a -40 dB/dec roll-off. The effect was thoroughly analyzed and as a result, we present a simple equivalent circuit model that successfully describes transistors operating in pushout up to very high frequencies.
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| 2. |
- Rohner, M., et al.
(författare)
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Velocity-modulation and transit-time effects in InP/InGaAs HBTs
- 2001
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 22:9, s. 417-419
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Tidskriftsartikel (refereegranskat)abstract
- The base-collector capacitance C-bc and the collector transit time delay tau
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| 3. |
- Rohner, M., et al.
(författare)
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Velocity modulation in III/V-HBTs
- 2003
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383 .- 1557-9646. ; 50:5, s. 1205-1213
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Tidskriftsartikel (refereegranskat)abstract
- Velocity modulation is shown to have a strong impact on the base/collector capacitance and the collector transit-time delay which dominate the high-speed performance of state-of-the-art HBTs. The authors present a theoretical analysis of the velocity modulation effects, which is the base of a method to assess their strength from measured S-parameters. Monte Carlo simulations are in good agreement with the measurements, providing strong support for the theory. As a consequence, the authors find that the carrier velocity is much lower than estimated from transit-time measurements when neglecting velocity modulation and that base-pushout occurs at much lower current levels than commonly expected.
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| 4. |
- Schwarz, V., et al.
(författare)
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56 Gbit/s analogue PLL for clock recovery
- 2001
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 37:22, s. 1336-1338
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Tidskriftsartikel (refereegranskat)abstract
- A clock-recovery circuit is reported that employs a phase-locked. loop (PLL) at 56.88 Gbit/s. and is demonstrate by locking to a 28.44 GHz sinosoidal signal while two additional circuits with adapted on-chip passive components are locked to 29 and 39 Gbit/s pseudorandom bit sequences, To the knowledge of the authors, this is the First demonstration of an integrated PLL integrated circuit for clock recovery at a data rate well above 40 Gbit/s.
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| 5. |
- Willen, Bo G., et al.
(författare)
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Experimental evaluation of the InP-InGaAs-HBT power-gain resonance
- 2002
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 23:10, s. 579-581
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Tidskriftsartikel (refereegranskat)abstract
- An InP-InGaAs HBT has been evaluated that exhibits resonant hole modulation effects at a sufficiently low frequency for the resonance to be completely characterized by network analyzer measurements. It is shown that the frequency dependence of both the unilateral power gain and the current gain are modified by this effect, thus affecting the associated cutoff frequencies f(max) and f(T). A new power gain expression G(P) based on measured small-signal parameters is introduced to circumvent the ambiguity in the unilateral power gain. Finding f(max) and f(T) by means of extrapolation of G(P) and h(21), respectively, from a region below the,resonance frequency is proposed to yield appropriate estimates of the figures-of-merit for device applications.
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| 6. |
- Willen, Bo G., et al.
(författare)
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Improved automatic parameter extraction of InP-HBT small-signal equivalent circuits
- 2002
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Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 50:2, s. 580-583
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Tidskriftsartikel (refereegranskat)abstract
- An improved automatic extraction technique for determination of the element values of an InP heterojunction-bipolar-transistor small-signal T-model is presented. Numerical optimization is shown to yield reproducible and physically relevant results when using a suitable figure-of-merit. The outcome of such an extraction is displayed for a range of operation points and the resulting bias dependencies of the element values is shown to be in good agreement with theoretical effects. The technique is further used to validate the quality of the extraction itself by showing a significant sensitivity to a deliberate error in the value of each element.
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| 7. |
- Willen, Bo G., et al.
(författare)
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Unilateral power gain limitations due to dynamic base widening effects
- 2001
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 22:8, s. 370-372
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the maximum frequency of oscillation of an InP-HBT may be limited by the low velocity of the holes when operated in the base push-out regime since modulation of the extended base will be delayed by the hole transit time, having an effect also on the electron current. The resulting delay of the current response causes a peaking of the unilateral power gain followed by a -40 dB/decade roll-off, being a source for a strong overestimation of the extrapolated cut-off frequency when neglected,An extended equivalent small-signal circuit is proposed that takes these effects into account.
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