Digitally controlled oscillator gain estimation for RF-DPLLs in 4G LTE polar transmitters

Buckel, T.; Tertinek, Stefan; Kanumalli, Ram Sunil; Mayer, Thomas; Wicpalek, C.; Weigel, Robert; Ussmueller, Thomas

doi:10.1109/iscas.2016.7539001

Cited by 2 publications

(3 citation statements)

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“…Measurements show that the OLGAA achieves an accuracy of approximately ±2%, which is only sufficient for GSM/EDGE. For other RATs such as UMTS or LTE-A, a much better accuracy as shown in [6] is required. Therefore, a subsequent gain estimation is performed by means of the DGE.…”

Section: B Open Loop Gain Auto Adjustmentmentioning

confidence: 99%

“…Since the DCO gain can change over temperature and operation point on the DCO fine-tuning field, the DGE is also utilized during signal transmission. Due to the flexible spectral allocation found in LTE-A uplink, the DGE has to handle signals with a very low-persistent excitation level resulting in a poor tracking capability as well as signals with a very high-excitation level and stringent requirements on the residual DGE error as shown in [6]. To achieve a proper convergence behavior of the estimated normalization gain, the step-width μ has to be chosen according to the signal statistics of the error signal u e .…”

Section: Dco Gain Estimationmentioning

confidence: 99%

“…It is shown that for increasing channel bandwidths, dense and clustered RB allocations exhibit a strong sensitivity to mismatches. The problem of changing RB allocations and signal characteristics influencing the DCO gain estimation (DGE) operation is discussed in [6].…”

mentioning

confidence: 99%

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A Highly Reconfigurable RF-DPLL Phase Modulator for Polar Transmitters in Cellular RFICs

Buckel¹,

Tertinek

Mayer

et al. 2018

IEEE Trans. Microwave Theory Techn.

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A multirate fractional-N RF digital phase-locked loop (DPLL) phase modulator implementation for polar transmitter supporting cellular communication standards up to 4G LTE-A is demonstrated. The RF-DPLL integrates LC-tank-based digitalcontrolled oscillator (DCO) cores with --noise shaping and fractional sample rate conversion to account for a broad range of frequency bands and spectral emission requirements. A twopoint modulation with different sampling rates and signal scaling is applied to optimize the system for operation in narrow-band and wide-band phase modulation. DCO digital predistortion and DCO gain estimation in combination with open-loop gain auto adjustment and delay calibration are implemented to achieve sufficiently low-in-band distortion. Measurement results of the RF-DPLL system as part of a polar transmitter implemented in 28-nm CMOS are shown, fulfilling 3GPP specifications for 4G, LTE-A uplink and legacy cellular communication standards like 3G, UMTS/HSPA+ and 2G, GSM/EDGE.

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Section: B Open Loop Gain Auto Adjustmentmentioning

confidence: 99%

Section: Dco Gain Estimationmentioning

confidence: 99%