I am looking to choose a PLL part that can do what I need:
I want to generate a 13.56MHz output signal based on an input reference freq also at 13.56MHz (locked to same frequency).
The challenge is that I need to be able to digitally adjust the phase between the output and the reference 13.56MHz, over a range of 0-180 degrees with at least a 1 degree resolution.
Can you recommend a PLL product that can accomplish this?
CTO, XP-Power RF Products Group
Essentially you need a fractional PLL with phase adjust that can operate down to 13 MHz and the ability to operate at N=1. I'm not aware of a PLL product in our portfolio that can meet all of those requirements.
Solutions that integrate phase adjust and will allow your 13.56 MHz REF to be retained will require operating the VCO at a higher frequency (avoids searching for a digital phase shifter that works at 13 MHz). Potential PLL solutions are the HMC703, ADF4355 / ADF4356 (min N = 23), ADF4372 (min N =20). The ADF4159 has phase adjust but the RF input doesn't appear to allow 13.56MHz. For the integrated VCO/PLL solutions (4355/4356 & possibly the 4372) where even with the output divider, 13.56 MHz still can not be achieved, you'd need to add a divider at the output. We have plenty to choose from so please visit analog.com and look under the RF and Microwave section. This divider of course can't be synchronized to those inside the PLL but after power up will still allow phase adjust. Additionally, if N must equal 1 then you'll need to incorporate this into a an offset / translation loop architecture.
The offset loop architecture may be able to be avoided but it will require you to locate a digital phase shifter that plays at 13MHz (closest we have is 1.2GHz). For the best phase noise at this frequency a high slew rate is required which equals a square wave (see HMC4069 plots for some good examples of this). Since you're wanting N to equal 1 I'm assuming noise is critical so there's a tradeoff here as you need phase adjust as well which necessitates a sine wave. A sine wave can be used at this frequency but it will need to be towards the upper end of the input drive level in order to keep the PFD working over temperature. The only parts that I'm aware of where customers have had success in achieving N=1 are our phase frequency detectors (HMC439 and HMC3716).
The PLL's with the lowest minimum N are INT N and based on the above phase detectors (HMC440, HMC4069 respectively) but the minimum N is restricted to 2. Since they are INT only there is of course no phase shift capability within the PLL.
Hope this helps,