Joint odd-even quantisation in cartesian delta-sigma (ΔΣ) upconverters

Analysis Predicted Location of Harmonic Distortion in RF Upconverter Structure

“…The research method is based on the analysis results in [2] and technically we use the similar equation derivation (part 2.1) for the reference carrier signal S k (f) as shown in Figure 2 and Figure 3. Later, two scenarios for the odd quantisation [3][4][5][6] scheme and even quantisation [2] scheme are chosen for the comparison results.…”

“…Agreement between simulation and calculation degrades as OSRRF is reduced. Two scenarios for the odd quantisation [3][4][5][6] and even quantisation [2] are chosen for this comparison at values of K = 1, fssb= 64 MHz, OSRRF = 32, and fc = 1024 MHz. The pulse width, α, is based on the expected pulse width for a given input signal amplitude.…”

“…PWM/PPM techniques are used to control the amplitude and phase of an RF carrier. But, the rectangular nature of the output pulse generates a number of unwanted harmonics and distortion products such as an image, 3rd harmonic, -3rd harmonic and other low-odd order harmonics [3][4][5].…”

“… Techniques can shape the noise away from the carrier band for subsequent removal in a band-pass filter [9] and make it suitable for high-precision data acquisition applications [10], but tunability remains a problem [6]. Our previous work in [6], it describes a method of tuning which is particularly suitable for schemes with high-resolution polar quantisers, such as the waveform PWM-mode Cartesian  [3][4][5]. The results recovers much of the dynamic range over the operating band.…”

“…Figure 1. Cartesian Σ∆ scheme which is applied for baseband tuning scenario and odd quantisation scheme [3][4][5][6].…”