This paper presents a 10-bit. 600 MS/s direct-sampling sub-Nyquist rate DAC-based frequency-agile wideband transmitter for IEEE 802. 22 cognitive radio applications in the VHF/UHF TV band (54 – 862 MHz). Multi-mode reconstruction using Gilbert cells. https://www.megavitamines.shop/product-category/pycnogenol/