PLLFH
u8 pllfh = itd1000_read_reg(state, PLLFH) & 0x0f;
itd1000_write_reg(state, PLLFH, pllfh | (itd1000_lpf_pga[i].pgaext << 4));
itd1000_write_reg(state, PLLFH, (itd1000_read_reg(state, PLLFH) & 0xf0) | ((pllf >> 16) & 0x0f));